Caltrans shares important tips for motorists heading to higher elevations this winter. The video also introduced drivers to Caltrans' new method of identifying chain installers who have been permitted and trained by Caltrans. Public Information Of McClatchyCaltrans

Caltrans shares important tips for motorists heading to higher elevations this winter. The video also introduced drivers to Caltrans' new method of identifying chain installers who have been permitted and trained by Caltrans. Public Information Of McClatchyCaltrans

An unusually cold storm blew through Northern California on Monday, bringing snow to Sierra foothills communities like Placerville and Grass Valley and rain to Sacramento.

Chain controls were installed on Interstate 80 and Highway 50 as the first storm of 2017 hit the region, slowing traffic for motorists returning home from the mountains following the extended New Year’s weekend. More precipitation was forecast for Tuesday and through the rest of the week.

Although it wasn’t one of the strongest storms of the season, it appeared that it would bring some drought relief. California needs snow, and previous storms this season had brought comparatively small amounts of snow despite heavier-than-usual rainfall.

“This week it looks like we’ll have a chance to add on to what’s already up there,” said Mike Kochasic, a National Weather Service forecaster in Sacramento.

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What made the storm so unusual was snowfall in communities as low as 1,000 to 1,500 feet. The weather service said Grass Valley could receive as much as 8 inches of snow Monday, and another 2 inches late Tuesday. Placerville’s forecast called for 1 to 2 inches Monday and up to three-quarters of an inch Tuesday. Auburn was told to expect about an inch by Tuesday night.

A winter weather advisory was in effect until late Monday night in much of the Sierra, including the foothills.

Chains were required at 6 a.m. Monday on vehicles traveling on Highway 50 from 3 miles east of Placerville to Meyers in El Dorado County. Low snow brought out the chain controls on I-80 from 3 miles east of Gold Run in Placer County to the Nevada state line at 6 a.m.

The cold storm system was expected to bring light, fine snow that rapidly accumulates and can easily be blown about, according to the weather service. The snow showers are predicted to be of the hit-or-miss variety, falling in some Sierra spots, but absent in others.

Earlier this month, Caltrans alerted the public that the new "tow plow" is in service on I-80. When activated, the tow plow will move to the right side of the pulling plow, allowing 28 feet of roadway to be cleared at once. A normal plow has a snow removal width of 10 to 12 feet. Motorists are advised to remain 100 feet behind the equipment when lights are flashing.

Until Monday, the winter storm season had been been some of a mixed bag. Rainfall had been abundant; the Department of Water Resources said precipitation in the Sacramento Valley was 166 percent of average as of late Sunday night. Rain was also above average so far in the San Joaquin Valley.

Snowfall had been another story, however. California’s statewide snowpack stood at just 67 percent of average through last Friday, the latest data available.

“We’ve basically had warmer-than-average storms,” said Michelle Mead, a warning coordination meteorologist at the weather service.

Snow is critical because a healthy snowpack acts as an additional set of reservoirs, bolstering the state’s overall water supply. In a decent year, the snowpack contributes about 30 percent of the state’s supplies, refilling reservoirs and canals during spring and summer and helping California steer through its five-year drought.

It wasn’t clear how far the latest storm would go toward improving snowpack conditions, which are measured continually by electronic sensors scattered around the mountains. The Department of Water Resources supplements the electronic measurements with manual surveys, the first of which is scheduled for Tuesday at Phillips, off Highway 50 near Sierra-at-Tahoe ski resort.

The advance forecast for Northern California calls for a strong system from the Gulf of Alaska Friday night. However, snow levels are expected to be higher than the low snow system being experienced Monday.

If the weather pattern holds for the Friday through Sunday system, significant amounts of rain could fall in the valley and snow could be heavy in the Sierra, according to the weather service.